If while tuning your radio this week you happen to stumble on some acappella Arabic chants or a muezzin calling Muslims to prayer, there's no reason to get alarmed. The Beeb hasn't been bought out by Al-Jazeera, nor is it the Taliban jamming the airwaves.

It's that time of year again, Ramadan, when apart from fighting back hunger and thirst from dawn till dusk, Britain's Muslims will also be struggling to run the clutch of radio stations they traditionally open up at this time of year.

Adopting an array of names ranging from the unimaginative but effective Radio Ramadan, to the more creative Fast FM, some 26 stations will be broadcasting this year across the length and breadth of the country, the highest number ever.

All of them are taking advantage of the little-known, but widely used, Restrictive Service Licence (RSL). RSLs have been available from the radio authority since 1991, allowing operators to broadcast for a flexible 28-day maximum over a 3km radius. They lend themselves to various purposes ranging from sport to religion.

Last year, the single biggest reason for RSL applications was religious, with Ramadan licences making up the largest slice of this segment. "One of the big problems we have in the Muslim community is that we don't have a platform to discuss our own issues because we lack our own media, and the RSL is a temporary solution," says Bashir Khan, a spokesman for Radio Ramadan in Manchester, which has been running the seasonal operation for six years, serving a potential audience of about 50,000.

Most Ramadan radio outfits are makeshift affairs running on low budgets garnered from sponsorships and donations, although some, like the Manchester station, do take on paid professionals for the period.

The seasonal media platform has been a godsend for women, whose voices, for reasons both religious and irreligious, rarely come across. Many of the Ramadan RSLs give over the afternoon to women's programmes dealing with health, diet and the family as well as more touchy subjects such as forced marriage and domestic violence. "These stations link us to the outside world. Throughout the year we're provided with absolutely no services - we can't go swimming or to sports centres, we can't go to some mosques - so this is a rare occasion for women to play their part in the wider community," says Ummi Adil, a presenter on Radio Ramadan.

This year will be Manchester Muslims' sixth on air but many operators have become increasingly dissatisfied with the RA's inability to keep pace with their ambitions. The RSL was always supposed to be a launchpad into the permanent sector. Now there are grumblings that it has become a ghetto.

"The local licensing system which demands you compete against commercial bidders is just too unrealistic an expectation. Communities are not businesses nor do they want to be," says Zahid Amin of Radio Ummah, a 24-hour internet radio station which also runs an annual RSL in east London. "Also the radio authority has bracketed Muslims into the Asian category so that when you do apply for a licence you're told that the Muslim community is already catered for."

There are technical limitations, too. In heavily built-up places, the 10 watt limitation on signals is usually not sufficient to cover the 3km range allowed for RSLs. Pirate stations are particularly partial to the RSL frequencies because of the ease with which they can drown out their signal.

Radio Ummah is one of the fortunate ones. It has secured a digital licence to broadcast nationwide, but Amin says it has come at a cost that is prohibitive to most would-be operators. And he says that, despite the prospect of digital opening up more frequencies, the outlook for religious broadcasting is bleak.

Last year, the RA launched a pilot scheme, Access Radio, to assess the viability of community radio. Of the 15 projects awarded one-year licences, two are Christian, one Afro-Caribbean, and two Asian. The only Muslim licensee, the Karimia Institute in Nottingham, has had to share its licence with an Asian women's group in the city. Manchester's Radio Ramadan, which has long badgered the radio authority for a permanent platform, says it was not even informed of the scheme.

Amin believes that the marginalisation of Muslims is by design rather than default. "Access Radio was supposed to cater for communities, but the truth is that it's simply not accessible to Muslims. They haven't licensed a single standalone Muslim radio station, which means that when it comes to evaluation there will be nothing for them to assess and our exclusion will also be programmed into the community tier," he says.

The radio authority is sensitive to suggestions of bias, saying the timetable for launching Access Radio was very tight. "In 15 projects you cannot encompass every single interest group in the UK," said Susan Williams, development officer in charge of RSLs. We wrote to as many RSLs as we could about the pilot, but we did not write to every single one."

· Faisal Bodi is a writer on Muslim affairs and editor of ummahnews.com.